Gas burner ignition system



y 8, 1965 P. ROMANELLI 3,183,959

\ GAS BURNER IGNITION SYSTEM Filed Feb. 25, 1963 3 Sheets-Sheet 1 BYMJLMW y 8, 1965 P. ROMANELLI 3,183,959

7 GAS BURNER IGNITION SYSTEM Filed Feb. 25, 1963 INVENTOR. ,4;- PaMnA szz/ Ma v May 18, 1965 Filed Feb. 25, 1963 P. ROMANELLI GAS BURNER IGNITION SYSTEM 3 Sheets-Sheet 3 BY M4 L ,arraeA/ars' United States Patent 3,183,959 GAS BURNER IGNHTIQN SYSTEM lat Romanelli, Bronx, N.Y., assignor to Ram Domestic Products Company, Englewood, N.J., a partnership Filed Feb. 25, 1963, Ser. No. 260,790 7 Claims. (Cl. 158-124) The present invention relates generally to heating units and specifically to an automatic ignition system for a gas fired device, which system offers improved safety and performance while at the same time minimizing manufacturing costs.

In a great number of installations, automatic ignition systems are required for the control of fuel flow and for the ignition of the fuel. Automatic ignition systems for household use in appliances such as gas fired clothes dryers must be versatile and should incorporate safety features precluding the possibility of dangerous performance. Although the ignition system according to the present invention was designed specifically for gas fired automatic clothes dryers, the concepts of the invention may be incorporated in a number of other devices since the ignition system for a gas dryer is of necessity extremely versatile. Specifically, automatic gas dryers are relatively simple appliances wherein a chamber is heated by a flow of burning fuel which flow is triggered by a thermostatic control. The heating may be suspended by the temperature control mechanisms, by the timing device tolling the end of the cycle of operation of the machine, by the opening of the door to the appliance, by interruption of electrical power to the appliance or by failure of an electrical component within the appliance.

Any one of these circumstances must automatically and immediately close thefuel valve. Furthermore, it is desired that the ignition and control system be capable of reactivating in a short period after halt of operations without any escape of unburned fuel. Although a number of automatic ignition systems have been designed and used commerically with some success, there exists a substantial need for improvements in reliability, operational characteristics, costs of manufacture and simplicity of installation into appliances.

Accordingly, it is generally the object of the present invention to provide an ignition and control system for gas fired units of improved characteristics. Specifically, it is an object of the present invention to provide an automatic ignition system to ignite and control the flow of fuel in a gas clothes dryer.

It is further within the contemplation of the present invention to provide an automatic ignition system incorporating safety devices which completely prevent the flow of unignited fuel.

It is still further within the contemplation of the present invention to provide an ignition element incorporating a temperature sensing mechanism of positive and foolproof characteristics which will prevent the flow of fuel at all times other than when provision is made to ignite such fuel.

It is further Within the contemplation of the invention to provide an automatic ignition system which may be constructed as one physical unit for easy installation into a clothes dryer or other gas fired appliance.

In general, it is the object of the present invention to provide an automatic ignition and fuel control device for use with automatic gas clothes dryers which incorporates a high degree of safety and reliability at a low manufacturing cost.

In accordance with one illustrative embodiment of the present invention there is provided an automatic fuel ignition system for a gas heater having a burner, a solenoid operated valve, and a source of power which is activated when the heat is to go on. The system com- ICC prises an ignition element in proximity to the burner, a normally closed electromagnetic valve for controlling the flow of gas to the burner and a temperature sensing element arranged to control the ignition element and the valve. A primary switch is connected in series with the power source and the fuel valve to control the flow of fuel. A secondary normally closed switch is connected in series with the ignition element and the power source for selective energization of the ignition element. The temperature sensing element is positioned in proximity to the ignition element and to the gas burner and includes a solid metallic bar which expands in response to increased temperature and which is operatively engaged with the primary and secondary switches for activating the primary switch in response to an initial increase in temperature and then the secondary switch in response to further increase in temperature. Thus the normally closed primary switch starts the flow of fuel after an initial increase in temperature in the vicinity of the igniter which is energized from the power source through the normally closed secondary switch. The burner then further heats the temperature sensing element to engage the secondary switch todeactivate the igniter. Linkage means are provided between the temperature responsive bar and the primary and secondary switches to activate same in sequence as stated above.

The above brief description as well as further objects,

features and advantages of the present invention will be best understood by reference to the following detailed description of a presently preferred embodiment when taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a unitized automatic fuel ignition system according to the present invention with a portion of the frame broken away to expose the several components;

FIG. 2 is a sectional view along the line 2-2 of FIG. 1 looking in the direction of the arrows illustrating the use of a vibrator as the ignition system in the present invention;

FIG. 3 is a sectional and partial view taken along the line 3-3 in FIG. 1 looking in the direction of the arrows illustrating the particular link means incorporated in this embodiment of the present invention to actuate the primary and secondary switches;

FIG. 4 is a schematic and diagrammatic view of the circuitry incorporated in the ignition and control system according to the present invention illustrating the use of the vibrating ignition element as shown in FIGS. 1, 2 and 3;

FIG. 5 is a schematic view of the safety interlock shown in FIG. 4 illustrating the position of the various mechanisms in their condition after use to deactivate the fuel valve and ignition element;

FIG. 6 is a schematic representation of the circuit according to the present invention similar to that shown in FIG. 4 with the exception of the use of a different ignition element from that in FIG. '4, specifically the use of a resistance element rather than the sparking element of FIG. 4; and

FIG. 7 is an elevational and partially sectional view of a varying form of temperature sensing device for incorporation into the system according to the present invention.

Referring now specifically to FIG. 1, there is shown one embodiment of the automatic ignition system according to the invention, generally designated by the numeral 10, all the components of which, are mounted upon a generally T-shaped frame 12 having at one end an enlarged chassis 14, a curved U-shaped frame 16 at the other end and an interconnecting leg 17. Mounted on the frame 12, at the chassis 1 4, and one on top of one another are the primary switch 18 which controls the flow of fuel and the secondary switch 2% which controls the energization of the ignition element. Also mounted on the chassis 14 is a vibrator 22 utilized as part of the sparking igniter as willbe described below and a coil operated relay 24 withits associated mechanisms to be more fully describedbelow. In addition, there is mounted a pivot arm 26 which is engaged with the mechanical actuating arms of the two microswitches 18 and 20 and which is pivoted on the chassis 14- at the pivot 28.

Mounted within the elongated portion of the frame 12 is the temperature sensing rod 30 which is positioned against the pivot arm 26 at one end at a point close to the pivot 28 and which abuts an insulated stop 32 at the other end adjustably set in the end of the U-sha-ped frame 16 by the adjustment nut 34. The rod 30 is loosely mounted within the frame 12 by means of the insulated blocks 36, 38 at two spaced locations on the leg 17 of the frame 12. It will be appreciated that upon an increase in temperature of the rod 34 the rod will expand. Since the rod 30 is rigidly held at one end by the stop 32 its other end will move slightly at the point at which it contacts lever 26 thus pivoting lever 26 about its pivot point 28 and moving the end of the lever 26 op osite from the pivot point 28 toward the switches 18, 20. As seen in FIG. 3, a dimple 26((1) is formed in the lever 26 adjacent the actuating button 3801) of the primary switch 18 to thus throw the switch 18 as the arm rotates prior to engagement with the actuation button 20(a) of the secondary switch. Further expansion of the rod 30 will be effective to further pivot the lever 26 about its pivot point 28 thus coming into contact with the actuating button 26(a) of the secondary microswitch 2% to throw that switch upon a further increase of temperature of the temperature sensing rod 30. Thus, the fuel valve will be opened by the primary switch 18 and after a delay the ignition elements will be deactivated.

Mounted parallel to the temperature sensing rod 36, and within similar openings formed in the insulating blocks 36, 38 is a vibrator rod 42. which is rotatable about its own axis. A first arm 44" extends radially outwardly from the vibrator rod 42 and is engaged with the insulated vibrating member 22(a) of the vibrator 22 such that energizati'on of the vibrator 22 will cause a vibrating rotation of the rod 42; A second radial extending arm 46 of the vibrating rod 42 is formed at the opposite end of the rod, within the bifurcated legs of the U-shaped frame 15, and has a contact-making tip 48 which is engaged with an enlarged contact formed on the temperature sensing rod 30. A still further extension 52 of the vibrating arm 42 is connected to a biasing spring 54 which is effective to make the normal position of the tip 48 engaged with the contact 50 of the temperature sensing bar 3%. A pair of brush contacts 56, 58 are secured Within the insulating block 38 and make contact respectively with the temperature sensing bar 30 and the vibrating bar &2. It will be appreciated that upon the application of an electrical potential to the brush contacts 55, 58 and upon the activation of the vibrator 22, a spark will be generated between the tip 48 of the vibrating bar 42 and the contact 500i the temperature sensing bar 36 which spark will be effective to heat up the bar 39 and which will also be effective to provide an ignition spark for igniting a flow of fuel. In the deviceaccording to the present invention the spark produced between the contacts 48, 5d effectively heats up the .bar 34 a -sufticient amount to move the lever 26 to activate the primary switch 18. The primary microswitch 2t) which'in turn deactivates the elements forming the spark between the contacts 418, 5%.

Further features of the system according to the present invention, and further understanding of the invention will be obtained by consideration of the schematic representation of the automatic ignition system it as shown in FIG. 4. A solenoid operated fuel valve 69 controls the flow of gas from apipe 62 into a conventional gas burner 64. Located immediately adjacent the burner 64 is an ignition device 66 which, in this illustrative embodiment, includes the vibrating rod &2 and the temperature responsive bar 36 which interact to form ignition sparks between the contact-making tip 43 of the vibrating rod 42 and the enlarged contact 50 of the temperature responsive bar 39. As will be described below, the fuel valve 69 is controlled by the primary switch 18 and the ignition device 66 is controlled to the secondary switch 20 in response to the expansion of the temperature responsive :bar 3%.

A power source, including the two power lines L1, L2, delivers electrical energy to the ignition system it The power lines are energized from a portion of the overall appliance in response to a demand for heat. Specifically, a thermostat in a gas dryer registers a low heat and closes a circuit to deliver a supply of electrical power to the lines L1, L2. The automatic ignition system It) then operates, in response to the input of power to the lines Lil, L2, to energize the ignition means 66, open the fuel valve 66 and ignite the gas burner 64 until such time as the thermostatic device in the gas dryer registers a sufticient amount of heat and power is removed from the lines L1, L2.

The specific electrical interconnections are as follows: A lead this extends from L1 to the center contact of the single pole double throw primary switch 13 which is normally connected to the first line M2 which is connected to the relay coil 194 of the relay 2.4. The

other end of the relay coil 1M is connected to lead 106 to line L2. Thus, upon energization of the power lines L1, L2 the relay coil 104 is energized through the primary switch 18. The relay 24 has two switches, a first holding switchltl and a safety switch 110. The holding switch 198 is connected directly between the power line L1 to the line 112 and the first side of the relay coil 104 through the line 114 and forms a holding circuit for the relay 24 which, after initial energization of the relay 24 through the primary switch 18, will maintain the coil 1% of the relay 24 energized irrespective of the position of the primary switch 18. As may be readily seen, the safety switch is connected through line 116 to the solenoid operated valve 66 such that the valve 60 may be energized only when the safety switch 110 is closed. At its other side, the safety switch 136 is connected in series, through the line 113, with a normally closed interlock safety switch 129, and then through a line 122 to the other power line L2.

At the start of operations of the/system it), electrical energy is delivered to the vibrator 22 through the connecting line 124 from L1 to oscillate the vibrating bar 42. The vibrator circuit continues through a connecting line 125, through the brush contact 58, to the vibrating bar 42 which is in contact with the temperature responsive element Stl. This portion of the circuit continues through the heat responsive element 36 through the other brush contact 5a and then to a line 126 to the normally closed secondary switch 20 The other cont act of the secondary switch 2t) is connected through a branch line-127 to the line 116 to the power line L2 thus completing a series circuit through the sparking ignition element 66 and the secondary switch 29. Upon thevibration of the" vibrator ZZthe gap between the contact making elements 48, 59 will be opened and closed thus producing a heat generating spark for heating the bar 39 and for creating an ignition spark for fuel at the burner 64. e

As the bar 30 is heated and exp'and against the stop 32;, the opposite side end of the bar 30 moves away from the stop 32 causing the pivot arm 26 to rotate about the pivot 28 thus bringing the first contact 26(a) intoen- V gagement with the actuatin armor button 1801) of the 3,1ss,95a

primary switch 18. The engagement of the arm 26 by the bar 30 close to the pivot 23 produces a relatively great motion multiplication. When the engagement of the primary switch occurs, the series connection from L1 of the power source through the primary switch to the coil 104 of the relay 24 is broken although the coil 104 is maintained in its energized form through the hold switch 103. The primary switch is then moved to its second position to connect the valve 60 to the power line L1 through the primary switch 18 and the valve energizing line 128. It will be appreciated that with the movement of the primary switch 18 into its second motion, the valve 69 will be in -a series circuit between the power lines through the primary witch 18, the safety switch 110 and the interlock switch 120 thus energizing the valve and opening same for the flow of fuel to the burner 64. The fuel at the burner 64 will be ignited by the spark at the ignition device 66. This ignited fuel will then burn until the fuel valve 60 is de-energized. With the increased heat generated at the burner 64, the temperature responsive element 30 will expand further to further rotate the pivot arm 26 until its second contact 26(1)) engages the activating arm or button 20(a) of the secondary switch 20. As may be seen in FIG. 4, this is effective to open the circuit to the vibrating rod 42 and the temperature responsive element 30, to deactivate the ignition device.

Further referring to FIG. 4, reference will now be made to the interlock switch 120 whose purpose is to de-energize the fuel valve 60 and the ignition device 66 in the event that the system is not functioning properly and specifically in the event that the temperature responsive element 30 fails, after a given period of time, to read a temperature sufiicient to move the pivot arm 26 to disconnect the secondary switch 20. The interlock switch 12b, in series with the safety switch 110 and therefore in the series circuit which power-s both the fuel valve 60 and the ignition device 66, comprises a movable switch arm 129 connected through the line 113 to the safety switch 116, and fixed ar-m 130 normally in contact with the movable arm 129 and connected through the line 122 to the power line L2. The movable arm 129 is normally held in engagement with the fixed arm 13%? by means of a bimetallic bar 132 which is rigidly supported on the base 14 of the ignition system frame 12 as shown in the lefthand portion of FIG. 1. It will be appreciated that if the bimetallic element 132 were bent toward the left as seen in FIG. 4, there would be no support for the movable arm 129 which would fall downwardly out of engagement with the fixed arm 130 thereby breaking the circuit through the switch 120. A resistance coil 134 is placed around the bimetallic element 132 and is in parallel with the ignition device 66. Specifically, it is connected at one end through line 136 to the power line L1 and to other end by means of the line 138 to the operating contact of the secondary switch 20. It will be thus appreciated that the resistance coil 134 will be energized through the secondary switch 21? at all times that the ignition device 66 is so energized. Upon heating of the coil 134 the bimetallic element 132 will progressively bend toward the left in a manner well known for such elements. ment 132 will move toward the left beyond the end 122(21) of the arm 129 thus removing upward support to the arm 129 which will then drop downwardly breakin g the circuit through the interlock switch 120, as shown in FIG. 5. By the proper selection of the particular re sistance coil 134 and the characteristics of the bimetallic element 132, the interlock switch 120 may be designed to disconnect the fuel valve 60 and the ignition device 66 after a predetermined period of time during which the heat responsive element 30 has failed to sense a sufficient amount of heat to move the pivot arm 26 to disengage the secondary switch 20.

The interlock heating coil 134 and the bimetallic arm Given sufficient time, the ele- 132 are essentially a timing device which limits the period of time for the energization of the ignition device in the system. Any such timing device, which may be operated in parallel with the ignition device to effect a disengagement with the interlock switch 126), may be incorporated within the system, it being understood that the present invention does not depend upon the particular components illustrated herein.

According to the present invention, the interlock is automatically reset by mechanisms in association with the coil operated relay 24. Specifically, a spring biased reset arm 140, pivoted at 142 is biased by the spring 144 to swing in a clockwise direction (as seen in FIG. 4) to engage the moving arm 129 of the interlock switch 120 and to return it to its closed position as seen in FIG. 4. However, the reset arm 140 is also subject to the magnetic field created by the coil 104 of the relay 24 such that the reset properties are ineffective during the period of energization of the coil 104. Thus, the interlock switch 120 cannot be reset until such time as the relay 24 is deenergized by the removal of electric power from the power lines L1, L2, thus insuring that the malfunction which caused the interlock 120 to operate in the first place will not cause repeated malfunctions of the ignition system 10. It should be noted that the bimetallic element 132 is preferably constructed in a generally L- shaped manner having a main leg 132 (a) and an ambientcompensating leg 132(1)) which automatically compensates for the variations in ambient temperature in a manner well known in the art.

It will be appreciated that it is the function of the safety switch 110 to insure that there is no period of free flow of gas if, by chance, the power source L1, L2, is energized at a time when the temperature responsive bar 30 is still in an expanded condition such that the primary switch is engaged with the fuel valve 60. Specifically, if the power source were tie-energized, and then immediately reenergized, as by a momentary power interruption, and if the temperature responsive element 30 had not contracted to the position shown in FIG. 4, a circuit would exist through the primary switch 18 from the power line L1 to the valve 60 and from the valve 60 through the safety switch 110 to the power line L2. However, the coil 104 of the relay 24 can be energized only if the primary switch is in its initial position as shown in FIG. 4. Therefore, if the rod 30 were not in the contracted position shown in FIG. 4, the safety switch 110 would be open thus preventing the energization of the fuel valve 60 thereby to prevent a free flow of gas prior to the ignition system being activated to a. point where positive ignition of released fuel is assured.

Now turning to FIG. 6, there is shown an automatic ignition system, generally designated by the numeral 10A which, in most respects, is identical with the ignition system 19 shown in FIG. 4. System 10A differs from system 10 only in the ignition element employed. Therefore, a specific recitation of the various constructions and circuitry of the system 10A will not be repeated and the various elements are labelled with the same reference numerals as appear in FIG. 4 and the description of FIG. 4 should be respectively applied to the schematic drawing of FIG. 6.

The system 10A employs a resistance ignition element, generally designated by the numeral 166, instead of the vibrating device 66. The ignition device 166 in FIG. 6 comprises a resistance coil which is connected to the primary witch through lead 126A which corresponds to the lead 126 in the system 10. The other side of the coil 168 is connected through a lead 124A, corresponding to the leads 124 and of the system 10 shown in FIG. 4. If necessary, a transformer may be utilized in the leads 124A, 126A to vary the current delivered to the coil 168. The resistance coil ignition device 166 functions within the system 10A in a manner completely analogous to the functioning of the vibrating ignition device 66 in the system it Specifically, upon initial energization of'the power lines L1, L2 the ignition coil 168 is energized through the secondary switch 29. The coil is effective to heat up the temperature responsive bar 30 in an amount sufficient to swing the pivot arm 26 into engagement with the primary switch to start the flow of fuel to the burner 64. This fuel is ignited by the ignition coil 168 and the burning fuel is then effective to further heat the temperature responsive bar 3% in an amount suflicient to move the pivot arm 25 into engagement with the secondary switch Zii at which time the ignition coil 16B (and the interlock coil 134) is dc-energized.

Referring to FIG. 7, there is shown a differing form of heat responsive element which is generally designated by the numeral 23% which may be substituted for the heat responsive element so illustrated in the preceding drawings. The heat responsive element 230 comprises an elongated hollow tube 232 having a closed end 234 and is filled with a liquid 236 such as mercury which expands upon increase in temperature. At the end of the tube 232. opposite from the closed end 234, there is an enlarged area 238 which is capped over with a resilient flexible diaphragm 240. A. connecting rod 237 is positioned within the tube 232 between the mercury 236 and the diaphragm 240. It will be appreciated that uponan increase in the volume of the fluid 236 within the element 230, the diaphragm 240' will be bowed outwardly by the connecting rod 237. An actuating stud 242 is secured to the center of the diaphragm 240 and is moved outwardly upon expansion of the fluid 236. It will be appreciated that the heat responsive element 23ft may be positioned within either of the ignition systems or MA as a substitution for the solid bar 30. As the ignition devices 66 or 166 are activated, the mercury 236 within the tube 232 will expand to move the diaphragm 249 and the actuating stud 242 toward the left. The stud 242 is engaged against the pivot arm 26 to rotate the same about the pivot point 28 to first actuate the primary switch and then to actuate the secondary switch as described above.

It will be appreciated that there is provided in accordance with the present invention an automatic ignition system for gas fired heaters which is effective to permit a flow of gas to start through a valve to a burner only when the ignition device is in condition to promptly and properly ignite the fuel such that there is no danger of the release of unignited gas. Further, in the device according to the present invention a positive heat measuring element is utilized to insure that gas is released only when the ignition element is properly functioning. A signifi cant advantage of the device according to the present invention is the positive safety feature provided by the positive temperature responsive element which progressively activates the primary and secondary switches insuring that fuel will flow only when the ignition element is capable of igniting the fuel and insuring that the ignition element will be deactivated only after the fuel has been ignited. Still further, a safety interlock is provided which turns off all of the operative portions of the ignition system after a predetermined period of time if the ignition element and/or the burner has failed .to produce the proper temperature. This automatic cutoff is automatically reset upon de-energization of the entire ignition system such that the system is capable of commencing a newcycle of operation without any requirement for servicing. In addition, the system incorporates a safety switch to insure that absolutely no gas is released through the fuel valve prior to an initial energization of the igniter.

It will be further appreciated that the gas ignition system according to the present invention provides 'all of these advantageous features in a simple structure which is easily adapted to be mounted on a single chassis for incorporation intoan appliance such that easy assembly is assured and that easy maintenance is guaranteed.

7 Although the above description presents a disclosure of one embodiment of the basic system and two or three variations, it should be realized that a number of other design variations may be made which depart from the specific structures disclosed without departing from the concepts of the invention. Therefore, the following claims should be construed broadly in a manner consistent with the spirit and scope of the invention.

What I claim is:

1. An automatic fuel ignition system in combination with gas fired devices having a source of electric power, a burner, and a normally closed electromagnetic fuel valve for controlling the flow of gas into said burner, said system comprising an ignition element in proximity to said burner for igniting same, a solenoid operated relay, a primary switch having a normal first position in which it connects the solenoid of said relay across said power source and a second position in which it connects said fuel valve across said power source for selectively energizing said valve to control the flow of fuel to said burner, a sec ondary normally closed switch connected in series with said ignition element and said power source for selectively energizing said ignition element, temperature sensing means in temperature-sensing proximity to said ignition element and to the burner including a temperature responsive element which expands when heated, a movable switch-control element positioned for engagement by said temperature responsive element upon expansion of the latter for movement into actuating engagement with said primary and secondary switches, said switch-control element moving sufiiciently to actuate said primary switch to open said fuel valve before engagement with said secondary switch upon an initial increase in temperature at said temperature responsive element caused by energization of said ignition element, said switch-control element subsequently engaging said secondary switch to deenergize said ignition element upon further expansion of said temperature responsive element in response to the increased temperature of the ignited burner, time-controlled means for die-energizing said ignition element and closing said fuel valve in response to the failure of said temperature responsive element to sense said increased temperature of the ignited burner within a preselected time period, said safety means comprising a time-controlled elementin series with said secondary switch and in parallel with said ignition element, and an interlock switch in series with said ignition element and with said fuel valve, said time-controlled element being operatively engaged with said interlock switch to open same after a predetermined period or" time during which said ignition element remains energized, said solenoid operated relay including a normally open safety switch connected in series with said interlock switch, said fuel valve and said ignition element, and a second normally open hold switch connecting the solenoid of said relay across said power source and forming a holding circuit therefor independent of said primary switch, said safety switch and hold switch closing upon the energization of the relay solenoid only when said primary switch is in its first position.

2. An automatic fuel ignition system according to claim 1 which also includes automatic reset means engaged with said safety means for resetting the same after said interlock switch has been opened, said reset means being operatively engaged with said relay and operable only when the solenoid of said relay is do-energized.

' 3. An automatic fuel ignition system according to claim 1 in which said interlock switch comprises a fixed contact arm and a movable contact arm, said time-controlled element comprising a bimetallic element underlying said movable contact arm and normally holding it in engagement with said fixed contact arm, and a resistance element in proximity to said bimetallic element for heating the latter, said resistance element being in series with .9 while said ignition element is energized and for moving said bimetallic element out of engagement with said movable switch arm whereby to open said interlock switch after said predetermined period of time when said secondary switch fails to open.

4. An automatic fuel ignition system according to claim 3 which also includes automatic reset means for said safety means, said reset means including a movable reset arm positioned to engage said movable contact arm, means biasing said reset arm in a direction to engage said movable contact arm and move the latter into engagement with said fixed contact arm, said relay solenoid when energized holding said reset arm remote from said movable contact arm, whereby said reset arm is operable to close said interlock switch only when said relay solenoid is de-energized.

5. An automatic fuel ignition system in combination with gas fired deviws having a source of electric power, a burner, and a normally closed electromagnetic fuel valve for controlling the flow of gas into said burner, said system comprising a unitary frame mounted adjacent said burner, an ignition element mounted on said frame in proximity to said burner for igniting the latter, a primary switch connected in series with said power source and said fuel valve for controlling the flow of fuel in said burner, said primary switch being normally biased to an open position and having a plunger depressible'to close said primary switch, a secondary switch connected in series with said power source and said ignition element for energizing the latter, said secondary switch being normally biased to a closed position in which said ignition element is energized and having a plunger depressible to open said secondary switch, said primary and secondary switches being mounted adjacent each other on said frame with the plungers thereof in alignment, temperature sensing means mounted on said frame in temperaturesensing proximity to said ignition element and to said burner, including a temperature responsive element which expands when heated, an arm movably mounted on said frame in position for engagement by said temperature responsive element upon expansion of the latter, and positioned to successively engage the plungersrof said primary and secondary switches, said arm moving sufficiently to depress the plunger of said primary switch before depressing the plunger of said secondary switch to open said fuel valve upon an initial increase in temperature at said temperature responsive element caused by energization of said ignition element, said switch control element subsequently depressing the plunger of said secondary switch to de-energize said ignition element upon further expansion of said temperature responsive element in response to increased temperature of the ignited burner, said ignition element comprising a vibrator rod rotatably mounted on said frame and having a terminal lateral arm having a contact tip, a contact portion on said temperature responsive element in intimate association with said contact tip, and means for producing a vibrating spark gap between said elements.

6. An ignition element according to claim 5 in which said temperature responsive element comprises a solid metallic bar mounted parallel to said vibrator rod and having said contact portion at one end thereof, the other end of said bar being in engagement with said movable arm.

7. An automatic fuel ignition system in combination with gas fired devices having a source of electric power, a burner, and a normally closed electromagnetic fuel valve for controlling the flow of gas into said burner, said system comprising a unitary frame mounted adjacent said burner, an ignition element mounted on said frame in proximity to said burner for igniting the latter, a primary switch connected in series with said power source and said fuel valve for controlling the flow of fuel to said burner, said primary switch being normally biased to an open position and having a plunger depressible to close said primary switch, a secondary switch connected in series with said power source and said ignition element for energizing the latter, said secondary switch being normally biased to a closed position in which said ignition element is energized and having a plunger depressible to open said secondary switch, said primary and secondary switches being mounted adjacent each other on said frame with the plungers thereof in alignment, temperature sensing means mounted on said frame in temperature-sensing proximity to said ignition element and to said burner, including a temperature responsive element which expands when heated, an arm pivotally mounted on said frame in position for engagement by said temperature responsive element upon expansion of the latter, said arm having a first projection positioned to engage the plunger of said primary switch and a relatively smaller second projection positioned to engage the plunger of said secondary switch, said arm moving sufficiently to depress the plunger of said primary switch before depressing the plunger of said secondary switch to open said fuel valve upon an initial increase in temperature at said temperature responsive element caused by energization of said ignition element, said switch control element subsequently depressing the plunger of said secondary switch to de-energize said ignition element upon further expansion of said temperature responsive element in response to increased temperature of the ignited burner.

References Cited by the Examiner UNITED STATES PATENTS JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L. MATTESON, 1a., Examiner. 

1. AN AUTOMATIC FUEL IGNITION SYSTEM IN COMBINATION WITH GAS FIRED DEVICES HAVING A SOURCE OF ELECTRIC POWER, A BURNER, AND A NORMALLY CLOSED ELECTROMAGNETIC FUEL VALVE FOR CONTROLLING THE FLOW OF GAS INTO SAID BURNER, SAID SYSTEM COMPRISING AN IGNITION ELEMENT IN PROXIMITY TO SAID BURNER FOR IGNITING SAME, A SOLENOID OPERATED RELAY, A PRIMARY SWITCH HAVING A NORMAL FIRST POSITION IN WHICH IT CONNECTS THE SOLENOID OF SAID RELAY ACROSS SAID POWER SOURCE AND A SECOND POSITION IN WHICH IT CONNECTS SAID FUEL VALVE ACROSS SAID POWER SOURCE FOR SELECTIVELY ENERGIZING SAID VALVE TO CONTROL THE FLOW OF FUEL TO SAID BURNER, A SECONDARY NORMALLY CLOSED SWITCH CONNECTED IN SERIES WITH SAID IGNITION ELEMENT AND SAID POWER SOURCE FOR SELECTIVELY ENERGIZING SAID IGNITION ELEMENT, TEMPERATURE SENSING MEANS IN TEMPERATURE-SENSING PROXIMITY TO SAID IGNITION ELEMENT AND TO THE BURNER INCLUDING A TEMPERATURE RESPONSIVE ELEMENT WHICH EXPANDS WHEN HEATED, A MOVABLE SWITCH-CONTROL ELEMENT POSITIONED FOR ENGAGEMENT BY SAID TEMPERATURE RESPONSIVE ELEMENT UPON EXPANSION OF THE LATTER FOR MOVEMENT INTO ACTUATING ENGAGEMENT WITH SAID PRIMARY AND SECONDARY SWITCHES, SAID SWITCH-CONTROL ELEMENT MOVING SUFFICIENTLY TO ACTUATE SAID PRIMARY SWITCH TO OPEN SAID FUEL VALVE BEFORE ENGAGEMENT WITH SAID SECONDARY SWITCH UPON AN INITIAL INCREASE IN TEMPERATURE AT SAID TEMPERATURE RESPONSIVE ELEMENT CAUSED BY ENERGIZATION OF SAID IGNITION ELEMENT, SID SWITCH-CONTROL ELEMENT SUBSEQUENTLY ENGAGING SAID SECONDARY SWITCH TO DEENERGIZE SAID IGNITION ELEMENT UPON FURTHER EXPANSION OF SAID TEMPERATURE RESPONSIVE ELEMENT IN RESPONSE TO THE INCREASED TEMPERATURE OF THE IGNITED BURNER, TIME-CONTROLLED MEANS FOR DE-ENERGIZING SAID IGNITION ELEMENT AND CLOSING SAID FUEL VALVE IN RESPONSE TO THE FAILURE OF SAID TEMPERATURE RESPONSIVE ELEMENT TO SENSE SAID INCREASED TEMPERATURE OF THE IGNITED BURNER WITHIN A PRESELECTED TIME PERIOD, SAID SAFETY MEANS COMPRISING A TIME-CONTROLLED ELEMENT IN SERIES WITH SAID SECONDARY SWITCH AND IN PARALLEL WITH SAID IGNITION ELEMENT, AND AN INTERLOCK SWITCH IN SERIES WITH SAID IGNITION ELEMENT AND WITH SAID FUEL VALVE, SAID TIME-CONTROLLED ELEMENT BEING OPERATIVELY ENGAGED WITH SAID INTERLOCK SWITCH TO OPEN SAME AFTER A PREDETERMINED PERIOD OF TIME DURING WHICH SAID IGNITION ELEMENT REMAINS ENERGIZED, SAID SOLENOID OPERATED RELAY INCLUDING A NORMALLY OPEN SAFETY SWITCH CONNECTED IN SERIES WITH SAID INTERLOCK SWITCH, SAID FUEL VALVE AND SAID IGNITION ELEMENT, AND A SECOND NORMALLY OPEN HOLD SWITCH CONNECTING THE SOLENOID OF SAID RELAY ACROSS SAID POWER SOURCE AND FORMING A HOLDING CIRCUIT THEREOF INDEPENDENT OF SAID PRIMARY SWITCH, SAID SAFETY SWITCH TO HOLD SWITCH CLOSING UPON THE ENERGIZATION OF THE RELAY SOLENOID ONLY WHEN SAID PRIMARY SWITCH IS IN ITS FIRST POSITION. 